CSR: Small: Collaborative Research: Exploring Portable Data Placement on Massively Parallel Platforms with Heterogeneous Memory Architectures

对于许多计算领域，包括银河系的模拟、社交网络的分析、股票交易的建模等，异质计算正变得至关重要。异质存储系统的编程是一个巨大的挑战，由于编程的复杂性和快速的硬件演变，在异质硬件和应用程序之间造成了主要的障碍。该项目旨在解决这一障碍，预计将显著减轻程序员处理底层内存系统异构性的负担。这项研究的结果还将使一些应用程序在未来的异构系统上的计算效率不断提高，这是科学、健康、安全和人类其他方面持续进步的关键条件。为了解决异构存储系统上的编程挑战，该项目研究了一个软件框架，由硬件规范语言、一套新颖的编译器和运行时技术以及高级内存性能建模组成。目标是开发一种系统解决方案，在给定复杂的异类存储系统的情况下自动放置数据，特别是在大规模并行平台上。通过该框架，程序员不必为不同的存储系统定制程序，同时，复杂的存储系统可以充分转化为高计算效率。该框架对程序进行转换，以便在运行时将数据放置在内存中的位置、何时和如何迁移等方面的程序定制到底层的异类内存系统，并实现近乎最佳的内存使用。

Heterogeneous computing is becoming crucial for many computational fields, including simulations of the galaxy, analysis of social networks, modeling of stock transactions, and so on. Programming heterogeneous memory systems is a grand challenge, and creates a major obstacle between heterogeneous hardware and applications because of the programming complexity and fast hardware evolution. This project aims to address this obstacle, and is expected to significantly relieve programmers from handling the underlying memory system heterogeneity. The outcome from this research will also enable continuous enhancement of the computing efficiency of a number of applications on future heterogeneous systems, which is a critical condition for sustained advancement of science, health, security and other aspects of humanity.To address the programming challenges on heterogeneous memory systems, the project investigates a software framework, consisting of a hardware specification language, a set of novel compiler and runtime techniques, and advanced memory performance modeling. The goal is to develop a systematic solution to automatically place data given a complex heterogeneous memory system, especially on massively parallel platforms. With the proposed framework, programmers are relieved from tailoring their programs to different memory systems, and at the same time, the sophisticated memory systems can get fully translated into high computing efficiency. The framework transforms the programs such that they are customized - in terms of where data are placed in memory, when and how to migrate, etc.- to the underlying heterogeneous memory system at runtime and attain a near optimal memory usage.